<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <style>
            body {
                font-family: "Courier New", Courier, monospace;
            }
            #d1 {
                color: red;
            }
            div {
                /* !important作用是提升优先级 */
                color: blue !important;
            }
        </style>
    </head>
    <body>
        <div id="d1">
            <p>这是个p标签</p>
            <span>这是div里面的span</span>
            <a href="#">超链接</a>
        </div>
        <span>这是div外面的span</span>
    </body>
</html>
